Been toying with this tournament list. Think it would be a lot of fun to play (though probably not for your opponent lol).
In terms of strategy:
>Coven Throne as General. The Vyrkos Pack Alpha command trait lets you use it amazing command ability (+1 hit/wound/save until next hero phase) one per turn per turn for free. Use it on the throne itself Turn 1 to get it to a 3+ save and then, once one of the two blobs of 20 GG is in place, transfer buff to them.
>Mannfred can buff the other blob of GG on the other flank with his +1 hit/wound command ability.
>2 big blobs of 40 zombies supported by a necromancer with the arcane tome and overwhelming dread which stacks well as a debuff with fading vigour on Mannfred. The low casting value and 18" range are excellent.
>Geminids to shut down command abilities on units which can't be negated by Hunters of the Heartlands (could sub this for shackles but it might effect your own units)
>The Vyrkos re-roll failed casts on the throne is good to improve the chances of getting Shudder off.